Heat treatment apparatus



HEAT TREATMENT APPARATUS Filed Nov. 25. 1964 5 Sheets-Sheet l 4 7 17 //1z I a 3 I l I l H I a-E1 11ml u HIIHH llll||[ w I W I Jan. 2, 1968 F. J. MORGAN HEAT TREATMENT APPARATUS 3 Sheets-Sheet 9 Filed Nov. 25. 1964 F. J. MORGAN HEAT TREATMENT APPARATUS Jan. 2, 1968 3 Sheets-Sheet 5 Filed Nov. 25. 1964 Q sNN United States Patent 3,361,420 HEAT TREATMENT APPARATUS Francis John Morgan, Sutton Coldfield, England, assignor to Wellman Incandescent Furnace Company Limited, Smethwick, England, a British company Filed Nov. 25, 1964, Ser. No. 413,720 Claims priority, application Great Britain, May 23, 1964, 21,385/ 64 2 Claims. (Cl. 266) ABSTRACT OF THE DISCLOSURE Apparatus for heat-treating articles comprising a foundation, an impeller rotatably mounted on a vertical axis above the foundation, a substantially horizontal and generally circular work-supporting plate which extends above the impeller and has a central aperture in alignment with the impeller, a detachable cover for enclosing articles on the work-supporting plate, which rests upon the foundation and is spaced from the periphery of the worksupporting plate, a series of walls arranged at regular intervals and spacing the work-supporting plate from the foundation, each of which extends generally tangentially from the impeller and curves outward so that its outer portion extends generally radially of the axis of the impeller toward the outer periphery of the work-supporting plate, to provide passages between the walls that flare gradually in their inner portions and flare abruptly in their outer portions, and a cooling coil substantially filling the outer end of each such passage which continuously ascends from one end to the other so that the coil is selfdraining.

Background of the invention This invention relates to heat treatment apparatus of the kind used for example for annealing workpieces such as steel strip coils and comprising a base on which the coils are placed, a primary cover enclosing the coils on the base and a secondary cover also supported on the base and enclosing the first cover; a fan or impeller is provided in the'base to circulate atmosphere within the primary cover and about the workpieces so as to render the temperature of various portions of the coils substantially uniform.

Hot gases are distributed through the space between the two covers to heat the workpieces for annealing by heat transfer through the primary cover and by circulation of the atmosphere therein. When an annealing cycle is completed the secondary cover is removed for use over another primary cover and stack of coils on another base while the original primary cover remains enclosing its work load while cooling takes place, thus preventing oxidation during cooling.

Summary of the invention The object of the present invention is to provide improvements in apparatus of the kind referred to and which are particularly adapted to accelerate the cooling stage of the treatment and which furthermore can be incorporated as modifications in existing apparatus with a minimum of disturbance to the foundations or structure thereof.

In accordance with the present invention heat treatment apparatus comprising a base for supporting a work load, at least one removable cover for enclosing the work load, and fan or impeller means for circulating atmosphere about the work load within the cover, is characterized by the provision of heat exchange means disposed in the base and in the path of circulation of the atmosphere within said cover.

The base may comprise an annular work supporting surface and a centrally located fan or impeller, preferably located below the work supporting surface and substantially radially of the fan, a number of supporting walls which define passages for the atmosphere, and the heat exchange means may be located in said passages.

Preferably but by no means essentially, the heat exchangers comprise coils of tube with the axes of the coils substantially normal to the plane of the base, the coils being connected so as to be self-draining.

While the coils may be connected to sources of supply of any suitable heat exchange fluid, it is preferred to util ze water which may be circulated through the coils by pump means and pass to further heat exchangers located externally of the apparatus or to cooling ponds at which heat gained during passage through the coils may be given up to atmosphere.

Brief description of the drawings One preferred embodiment of the present invention will now be more particularly described with reference to the accompanying drawings, wherein:

FIGURE 1 is a largely diagrammatic sectional elevation of an installation for annealing coils of steel strip;

FIGURE 2 is an enlarged sectional plan of the base of the apparatus taken on line 2-2 of FIGURE 3.

FIGURE 3 is a sectional elevation on the base taken on the line 33 of FIGURE 2.

FIGURE 4 is a sectional view taken on the line 4-4 of FIGURE 2.

Description of the preferred embodiment Referring now to the drawings and in particular to FIGURE 1, the apparatus comprises a base 10 provided with an annular work supporting surface 11 and having a centrally located fan or impeller 12 driven from a motor unit 12*. Stacked upon the base is a series of coils of sheet steel strip 13 with intermediate spacers 14. A cover 15 of comparatively thin material having a high coefiicient of conductivity encloses the coils 13 and seats upon the base 10, provision being made in the construction for a layer of sand or other sealing material to surround and seal the lower edge of the cover. Also located on the base is a secondary cover 16 which may be lined with refractory material and which has connections such as 17, 18 to facilitate circulation of heated atmosphere such as the products of combustion of a fuel, through the space between the two covers 15, 16.

In use heated atmosphere is circulated through the space between the two covers and by conduction through the primary cover 15 heats the atmosphere therein so as to heat treat the workpieces 13. The atmosphere in cover 15 is circulated by a fan to render the temperature throughout the interior of the cover 15 substantially uniform.

When the heat treatment step is concluded the cover 16 may remain in place for a time while the atmosphere in the inner cover 15 is circulated through a recuperator, but subsequently the cover 16 is removed and circulation of atmosphere within the cover 15 continues until temperature of the workpieces is reduced to a satisfactory level.

To this end, and referring particularly to FIGURES 2. to 4, the work supporting surface 11 is spaced from the foundation of the base 10 upon a series of walls 19, each of which extends generally tangentially of the fan or impeller adjacent the latter and then generally radially of the axis of the fan towards the outer periphery of the base. The space between the work supporting surface 11 and the foundation in which the walls 19 are located is enclosed by a peripheral skirt Wall 20 (FIGURE 3) which leaves an opening 21 through which atmosphere may be drawn by the impeller so that the atmosphere flows generally radially in the passages between the walls 19 to the fan and then axially through the cover about the coils and also between the convolutions of each coil until it returns to the said gap 21; the opposite flow path may be utilized depending upon the design of fan or impeller in use.

In each passage between each two adjacent walls 19 is located a heat exchanger coil 22, and the coils are connected in pairs as best shown in FIGURES 2 and 4 with an inlet connection 23 to one coil passing through the foundation and an outlet connection 24 from the connected coil passing parallel and likewise through the said foundation. The top ends of the two coils which are helical and have parallel axes, are connected by a header tube 25 which is inclined downwardly to each coil froma center point as will be best appreciated from FIGURE 4 of the drawing, so that the coils are self-draining to 'minimize corrosion when not in use.

The coils may be connected to manifolds and distribution controlling valves so that cold heat exchange fluids such as water may be circulated through each pair of coils and warm or hot water withdrawn for cooling in external heat exchangers, cooling ponds or the like. Hence the atmosphere within the cover 15 is continuously cooled when the system is in operation and the cooling ment with the impeller, and a detachable cover for enclosing articles on the work-supporting plate, which rests upon the foundation and is spaced from the periphery of the work-supporting plate, wherein the improvement comprises a series of walls arranged at regular intervals and spacing the work-supporting plate from the foundation, each of which extends generally tangentially from the impeller and curves outward so that its outer portion extends generally radially of the axis of the impeller'toward the outer periphery of the work-supporting plate, to provide passages between the walls that flare gradually in their inner portions and flare abruptly in their outer portions, and a cooling coil substantially filling the outer end of each such passage which continuously ascends from one end to the other so that the coil is self-draining.

2. Apparatus according to claim 1 wherein adjacent pairs of cooling coils are connected at their upper ends, the lower end of one coil of each pair extending downward to form an inlet connection, and the lower end of the other coil of each pair extending downward to form an outlet connection.

References Cited UNITED STATES PATENTS 3,140,743 7/1964 Cone e66 5x 3,100,634 8/1963 Rubrechtetal. 2,479,814 8/1949 Cone. 2,245,647 6/1941 Burby etal 266-5 1,985,950 1/1935 Resek an 29 157.3 X 2,789,808 4/1957 Blackman.

FOREIGN, PATENTS 1,197,727 12/1959 France.

455,089 10/1936 GreatBritain.

JOHN F. CAMPBELL, Primary Examiner. I. CLINE, Assistant Examiner. 

